http://yetl.yabesh.ir/yetl1/handle/yetl/19030 2026-04-30T09:19:15Z 2026-04-30T09:19:15Z Incheol Kim Seungho Kang Youngjin Ko Junhwan Lee http://yetl.yabesh.ir/yetl1/handle/yetl/4309481 2026-02-16T21:37:10Z 2025-01-01T00:00:00Z

Characterizing Effects of Changes in Soil Phase on Elastic Wave Velocities for Sand with Different Moisture Contents Incheol Kim; Seungho Kang; Youngjin Ko; Junhwan Lee Geohazards such as slope failures and retaining wall collapses have been observed during thawing season, typically in early spring. These geohazards are often attributed to changes in the engineering properties of soil through changes in soil phase with moisture condition. This study investigates the impact of freezing and thawing on soil stiffness by addressing shear wave velocity (Vs) and compressional wave velocity (Vp). An experimental testing program with a temperature control system for freezing and thawing was prepared, and a series of bender and piezo disk element tests were conducted. The changes in Vs and Vp were evaluated across different phases: unfrozen to frozen; frozen to thawed; and unfrozen to thawed. Results indicated different patterns of changes in Vs and Vp during these transitions. Vs showed an 8% to 19% decrease for fully saturated soil after thawing, suggesting higher vulnerability to shear failure-related geohazards in thawing condition. Vp showed no notable change after thawing compared to initial unfrozen condition. Based on the test results in this study, correlation models for Vs and Vp with changes in soil phase of unfrozen, frozen, and thawed conditions were established. From computed tomography (CT) image analysis, it was shown that the decrease in Vs was attributed to changes in bulk volume and microscopic soil structure.

2025-01-01T00:00:00Z Rowena Stevenson Elisabeth Bowman http://yetl.yabesh.ir/yetl1/handle/yetl/4309480 2026-02-16T21:37:08Z 2025-01-01T00:00:00Z

Effective Stress and Suffusion Onset at Local and Global Scales in Centrifuge Permeameter Tests Rowena Stevenson; Elisabeth Bowman This study presents the results from a series of centrifuge tests conducted in a novel permeameter capable of measuring both global and layer permeability. Six tests were undertaken at gravitational accelerations ranging from 10 to 40g. Using a parametric modeling approach, the research examined the influence of effective stress gradient on the onset and progression of suffusion in an underfilled, gap-graded soil. At a specimen scale, increased effective stress gradient appeared to increase suffusion susceptibility in identically prepared models. However, analysis of the permeability response of individual layers indicated that initial microscale variability and hydraulic loading history had more impact on the suffusion behavior than did effective stress. At the layer scale, suffusion and clogging events occurred from the onset of seepage flow, and there was no observed influence of effective stress level on suffusion onset. The study found that the definition of suffusion onset is highly dependent on experimental design, and critically evaluated the concept of threshold hydromechanical conditions for suffusion onset.

2025-01-01T00:00:00Z Yuting Zhang Jinsong Huang Anna Giacomini Jiawei Xie Jianlin Lu http://yetl.yabesh.ir/yetl1/handle/yetl/4309479 2026-02-16T21:37:07Z 2025-01-01T00:00:00Z

Robust Calibration of Shaft and Base Resistance Factors for Piles Based on Multiobjective Optimization Yuting Zhang; Jinsong Huang; Anna Giacomini; Jiawei Xie; Jianlin Lu Resistance factors are used to account for the uncertainties associated with pile resistance in load and resistance factor design (LRFD). Current design codes and most previous studies recommend a single resistance factor applied to the total pile resistance (shaft and base resistances). However, the uncertainties associated with shaft and base resistances are significantly different. Moreover, resistance factors are generally calibrated based on the statistics of resistance bias factors derived using all data collected from different sites, whereas the variability of the statistics between various sites (i.e., cross-site variability) has been ignored in the traditional calibration approaches, which may result in the designs based on the calibrated resistance factors violating safety requirements. In this paper, a robust calibration approach is proposed to calibrate shaft and base resistance factors, explicitly considering the cross-site variability in the statistics of resistance bias factors in the calibration process. To achieve that, the feasible robustness concept is adopted to describe the probability that the design remains able to achieve the target reliability index when the statistics of resistance bias factor exhibit cross-site variability. The calibration process is implemented through a multiobjective optimization, which leads to a Pareto front that describes the trade-off relationship between shaft and base resistance factors and feasible robustness. The optimal shaft and base resistance factors are determined using the minimum distance approach. The proposed approach is demonstrated and applied to calibrate shaft and base resistance factors for three design methods, the Vesic, Meyerhof, and Nordlund methods. Results show that resistance factors are significantly affected by design methods and the ratio of shaft and base resistances.

2025-01-01T00:00:00Z David Perozzi José Andrade Rolf Kaufmann Alexander M. Puzrin http://yetl.yabesh.ir/yetl1/handle/yetl/4309478 2026-02-16T21:37:05Z 2025-01-01T00:00:00Z

LS-DEM Guided Analysis of Geotechnical Tests: Exploring Strength Anisotropy and Stress Dependency David Perozzi; José Andrade; Rolf Kaufmann; Alexander M. Puzrin Reliable interpretation of model tests in geotechnical engineering often is hampered by the limitations of traditional laboratory element testing, especially under low-stress conditions and unconventional stress paths. This paper presents a pragmatic hierarchical multiscale numerical approach that combines the level set discrete-element method (LS-DEM) and continuum-based analysis to improve the interpretation of scaled geotechnical tests. LS-DEM enables high-fidelity simulations of soil behavior, overcoming challenges such as boundary effects and metrological limitations that make accurate assessments under specific conditions in standard laboratory tests difficult. The virtual LS-DEM specimens can be calibrated reliably using traditional laboratory tests, such as oedometer and triaxial tests. This approach was demonstrated and implicitly validated through its application to a study of displacement-dependent earth pressure on retaining walls. Key findings include the identification of additional kinematic constraints under plane strain conditions as the primary factor behind the high peak strength observed in scaled tests, and the observation that the strength of granular materials is negligibly affected by changes in stress level. In addition, the observation of pressure-dependent elastic parameter trends, consistent with previous studies, further validates LS-DEM as a reliable tool for quantitatively capturing the behavior of granular materials. By reducing reliance on semiempirical scaling laws and providing a robust framework for informing continuum-based models, this LS-DEM–based hierarchical approach effectively bridges the gap between small-scale laboratory experiments and large-scale geotechnical applications. Ultimately, this methodology enhances the design and analysis of geotechnical structures with greater confidence and accuracy, providing a practical and effective tool for addressing complex geotechnical engineering challenges.

2025-01-01T00:00:00Z